Diabetes insipidus (DI) is caused by:

Diabetes insipidus (DI) is caused by:

• A. A lack of ADH
• B. Excess ADH
• C. Lack of insulin
• D. Excess cortisol

Answer: (A)

Diabetes insipidus is caused by insufficient action of antidiuretic hormone. ADH’s job is to tell the kidneys’ collecting ducts to reabsorb water, concentrating the urine. When ADH is deficient (central DI) or the kidneys don’t respond to it (nephrogenic DI), water reabsorption drops dramatically, leading to huge volumes of very dilute urine and excessive thirst. The other options point to problems with insulin, cortisol, or excess ADH, which affect different endocrine systems and don’t produce the hallmark DI pattern of dilute, high-volume urination.

Diabetes insipidus is caused by insufficient action of antidiuretic hormone. ADH’s job is to tell the kidneys’ collecting ducts to reabsorb water, concentrating the urine. When ADH is deficient (central DI) or the kidneys don’t respond to it (nephrogenic DI), water reabsorption drops dramatically, leading to huge volumes of very dilute urine and excessive thirst. The other options point to problems with insulin, cortisol, or excess ADH, which affect different endocrine systems and don’t produce the hallmark DI pattern of dilute, high-volume urination.